Cut the beef across the grain into thin slices. Add the marinade ingredients and marinate for about 15 minutes.

While the beef is marinating, prepare the other ingredients. Trim the string beans. Blanch the string beans briefly in boiling salted water until they turn bright green. Remove the string beans, plunge briefly in ice cold water and drain thoroughly.

Peel and chop the garlic. In a small bowl, mix together the sauce ingredients. In a separate small bowl, dissolve the cornstarch in the water.

Heat the wok. Add 2 tablespoons oil to the heated wok.

When the oil is hot, add the chopped garlic and stir-fry until aromatic (about 30 seconds). Add the beef and stir-fry until it changes color and is nearly cooked through. Remove and set aside.

Clean out the wok with a paper towel if necessary, reheat and add 2 tablespoons oil. When the oil is ready, add the string beans. Stir-fry briefly, adding 1/4 teaspoon salt, sugar, or a seasoning such as Accent if desired.

Push the beans up to the sides of the wok. Add the sauce in the middle of the wok. Give the cornstarch/water mixture a quick re-stir and add to the sauce, stirring to thicken.

Add the beef back into the pan. Stir everything together and serve hot.